Loop taker for sewing machines



March 19, 1968 s. J. KETTERER LOOP TAKER FOR SEWING MACHINES 2 Sheets-Sheet 1 Filed April 7, 1966 INVENTOR. Sfanley J. Keflerer BY W2TORNEY March 19, 1968 5. J. KETTERER LOOP TAKER FOR SEWING MACHINES 2 Sheets-Sheet 2 Filed April 7. 1966 Fig.6.

INVENTOR. Stanley J. Ketferer BY XTTORNE Y United States Patent ()flice 3,373,7W7 Patented Mar. 19, 1968 3,373,707 L901 TAKER FOR SEWKNG MAQHINES Stanley J. Ketterer, Morris Plains, N.J., assignor to The Singer Company, New York, N.Y., a corporation of New Jerse Filed Apr. 7, 1966, Ser. No. 540,932 6 Claims. (Cl. 112-184) ABSTRACT OF THE DISCLOSURE A rotating loop taker for a lock stitch sewing machine is disclosed in which the loop taker body is formed with a flat planar bearing surface on which the bobbin case bearing flange rests. A bracket carried on the machine frame supports three bobbin case locating means each engaging the bobbin case flange and providing for constraint of the bobbin case radially, angularly and axially of the loop taker body.

This invention relates to a loop taker for lock stitch sewing machines and more particularly to a rotary hook, that is to say, a lock stitch loop taker in which the loop seizing beak engages and carries a needle thread loop about a thread carrying bobbin and then sheds the needle thread loop.

It is an object of this invention to provide a novel and advantageous rotary hook construction for a sewing machine including a rotary loop taker body carrying the thread engaging beak, a bobbin case, and a stationary bobbin case constraining bracket in which the bracket provides the sole constraint for the bobbin case radially, angularly and axially of the loop taker body. This novel arrangement eliminates the necessity for the conventional bearing raceway between the loop taker body and the bobbin case and provides instead simply planar bearing surfaces of engagement therebetween. As a result, the problem of thread jamming in the raceway is obviated, and moreover, the seized needle thread loop may be simply expanded and carried about the bobbin case without the necessity of imparting a twist thereto as is commonly required in conventional rotary hooks.

With the above and additional objects and advantages in view, as will hereinafter appear, this invention comprises the devices, combinations, and arrangements of parts hereinafter described and illustrated in the accompanying drawings of a preferred embodiment in which:

FIG. 1 is an exploded perspective view of the loop taker body, bobbin case, bobbin, and bobbin case constraining bracket,

FIG. 2 is a bottom plan view of the bobbin case,

FIG. 3 represents a vertical cross sectional view taken along the axis of the loop taker and illustrating the manner in which it is carried in a sewing machine,

FIG. 4 is a top plan view of the loop taker carried in a sewing machine with the slide cover and throat plates removed to expose the loop taker,

FIG. 5 represents a top plan view of the loop taker and includes a representation of the sewing threads as the needle thread loop is carried initially toward the bobbin case,

FIG. 6 represents a top plan view of the loop taker similar to FIG. 5 but illustrating the position of the sewing threads as the loop taker beak carries the needle thread loop about the bobbin case.

FIGS. 3 and 4 illustrate a portion of the sewing machine frame 11 in which the loop taker of this invention is carried. As illustrated the sewing machine frame is preferably formed with an upwardly open compartment 12 for the loop taker, which compartment is formed with an upper shelf 13 which accommodates a slide cover plate 14 and a throat plate (not shown). The compartment 12 is also formed with an intermediate shelf 15 and with a bottom wall 16 formed with a boss 17 adapted to provide the support for the loop taker.

The compartment 12, in addition to accommodating the loop taker of this invention, may also accommodate a feed dog 18 of a conventional drop mechanism which may be opposed by a conventional presser foot 19 as illustrated in FIG. 3. FIG. 3 also illustrates a fragment of a thread carrying needle 20 which together with the presser foot may be supported in another portion of the sewing machine frame (not illustrated), and to which needle endwise reci-procatory motion may be imparted in the conventional fashion.

The loop taker, which is indicated generally as in the drawings, includes a loop taker shaft 26 which is journaled in a bushing 27 secured by a set screw 28 in the boss 17 of the sewing machine frame compartment 12. For imparting rotary movement to the loop taker in timed relation with the reciprocation of the needle, a bed shaft 29 is journaled in a bushing 30 secured as by set screws 31 in the sewing machine frame 11 and the bed shaft 29 is rotated by conventional operative connection with the needle reciprocating means (not shown). A pair of meshing bevel gears 32 fast one on the bed shaft 29 and the other on the loop taker shaft 26 serve to drive the loop taker and the speed ratio of loop taker rotation relatively to needle reciprocation, whether obtained by the gearing 32 or by selection of parts of the actuating mechanism (not shown), is preferably two revolutions of the loop taker for each reciprocation of the needle.

As illustrated in FIG. 1, secured to or forming an integral part of the upper extremity of the loop taker shaft 26 is the loop taker body which is generally cup-shaped and includes a fiat bottom wall 41 and a cylindrical side wall 42 encompassing an upwardly open cavity 43. The rim 44 of the loop taker body is preferably formed as a planar bearing surface disposed in a plane perpendicular to the axis of the loop taker shaft 26 so as to provide a bearing surface for the bobbin case as will be described hereinbelow. The cylindrical side wall 42 of the loop taker body is formed with an inwardly directed needle loop engaging beak 45 which is defined by a radially inclined vertical slot 46 formed in the side wall 42. The slot 46 widens into a thread accommodating groove 47 beneath the beak 45. The cylindrical side wall 42 of the loop taker body is formed radially outwardly of the loop seizing beak 45 with a projection 48 which together with the beak 45 defines a thread accommodating notch 49 which limits movement of seized thread loops radially outwardly along the beak 45. The bottom wall 41 of the loop taker body is formed with an arcuate needle accommodating clearance slot 50 extending on that side of the loop taker body which is occupied "by the loop seizing beak 45. Beneath the loop seizing beak 45 and extending for short distance immediately in front of the beak, the side wall 42 of the loop taker body is formed with a radially inwardly extending projection 51 terminating flush with the needle clearance slot 50 and serving as a guide assisting in accurately positioning the needle relatively to the loop taker beak. The loop taker beak 45 may, in addition, be formed with a small radially inward projection 52 so that it extends radially inward to a slightly greater degree of the remaining cylindrical side Wall 42 of the loop taker body which favors seizure of needle thread loops thereby.

The bobbin case, which is indicated generally as 60, includes a generally cylindrical central portion 61 formed with a cylindrical bobbin accommodating cavity 62 which is upwardly open and formed at the bottom with a radially inwardly extending ledge 63 adapted to engage and support the bottom flange 64 of a conventional flanged bobbin 65. The cylindrical central portion 61 of the bobbin case may be formed with one or more shallow rim indeniations 66 providing space for an operators finger tips to grip the upper flange 67 of the bobbin in order that bobbins may be replaced or exchanged easily. A bobbin thread tensioning spring 68 is secured by a fastening screw 69 on the outer surface of the central cylindrical portion of the bobbin case. The bobbin thread tensioning spring is formed with a tang 70 in the end remote from the fastening screw 69, which tang is seated'in an aperture 71 in the bobbin case. A radially inclined thread slot 72 is formed in the central cylindrical portion of the bobbin case beneath the bobbin thread tensioning spring 68 and a thread guiding notch 73 is formed in the rim of the central cylindrical portion 61 of the bobbin case above the blind extremity 74 of the thread slot 72 so that a bobbin thread when drawn into the thread guide slot 72 will extend from the thread guide slot between the spring 68 and the central cylindrical portion 61 of the bobbin case and then into the notch 73. An adjusting screw 75 threaded into the central cylindrical ortion 61 of the bobbin case serves to provide for adjustment of the tension applied by the spring 68 upon the bobbin thread.

Extending radially outward from the central cylindrical portion 61 of the bobbin case is a bearing flange 76 preferably disposed substantially perpendicular to the axis of the cylindrical central portion 61 of the bobbin case. The undersurface 77 of the bearing flange 76 presents a planar bearing surface for engagement with the planar rim 44 of the loop taker body. The bearing flange 76 presents a circular peripheral portion 78 extending about a slightly less than half the circumference of the bobbin case. The bearing flange is slabbed as at 79 along a chord relatively to the cylindrical central portion of the bobbin case and adjacent to the slabbed portion 79 the bearing flange is formed with a radially inwardly extending notch 80.

The bobbin case constraining bracket, which is indicated generally as 90, is best illustrated per se in FIG. 1 and illustrated in relation to the loop taker and bobbin case in assembled relation in FIGS. 3 to 6. The bracket 90 is preferably made of two sheet metal plates 91 and 92 which are assembled in overlapping relation and have aligned apertures 93 and 94 to accommodate fastening screws 95 and 96 by which the plates are secured on the intermediate shelf in the loop taker compartment 12 of the sewing machine frame, with the lower plate 92 disposed in the plane of the bobbin case bearing flange 76 and the plate 91 disposed above the level of the bobbin case bearing flange. It will be understood that the construction including separate plates 91 and 92 is for convenience for manufacture and that the bracket 90 may be formed as an integral piece if desired.

The lower plate 92 of the bracket 90 is formed with a curved inner edge 97 including spaced segments 98 and 99 which are concentric and of identical radius with that of the circular peripheral portion 78 of the bobbin case hearing flange 76. That portion of the curved grooved inner edge 97 of the plate 92 which extends between the segments 98 and 99 is formed of greater diameter so that as illustrated in FIGS. 4, 5 and 6 only the segments 98 and 99 will abut the bobbin case hearing flange to constrain the bobbin case radially with respect to the loop taker body. The circular segments 98 and 99 thus provide a first abutment means on the bracket 90 and serve to constrain the bobbin case radially of the loop taker body into a position within the axial projection of the annular bearing surface 44 on the loop taker rim. The sheet metal plate 91 which overlies the plate 92 is formed with a curved inner edge portion 100 which includes segments 101 and 102 having radii substantially less than that of the periphery 78 of the bobbin case hearing flange 76.

Since the plate 91 occupies a position above the level of the bobbin case bearing flange the curved edge portion segments 101 and 102 being of smaller radius than the bearing flange periphery provide second abutment means on the bracket 90 which engage the bobbin case flange at the side opposite the flat annular bearing surface 44 of the loop taker body rim to constrain the bobbin case axially of the loop taker body. The plate 91 of the bracket also includes an arm 105 which extends in chord-like fashion diametrically across the arc defined by the circular segments 101 and 102. The arm 105 is also downwardly offset below the level of the remainder of the plate 91 so that when the plate 91 is secured in the machine frame, the arm 105 will extend in substantially co-planar relation with the bobbin case hearing flange 76 and will occupy a position adjacent to the slabbed portion 79 of the bobbin case bearing flange. The arm 105 of the bracket 90 will thus provide a third abutment means on the bracket which when assembled on the sewing machine frame will extend across the loop taker body and engage the slabbed portion 79 of the bobbin case bearing flange to constrain the bobbin case against circular movement with the loop taker body. As illustrated in FIG. 1 the arm 105 may include a shallow recess 106 across the central portion thereof so as to engage the bobbin case flange slabbed portion 79 only at spaced points of abutment 107 and 108, and the free extremity 109 of the arm 105 is preferably down turned to obviate the possibility of thread loops being inadvertently caught thereon,

Referring to FIGS. 4, 5, and 6, the manner in which the loop taker of this invention manipulates the sewing threads in the formation of lock stitches will now be described. FIG. 4 illustrates the position of the parts at the moment the loop taker beak seizes a loop of thread from the needle. In the drawings the needle thread is indicated as N and the bobbin thread as B. The bobbin thread B during sewing will extend from the thread guiding notch 73 in the bobbin case across the top of the bobbin and bobbin case and thence to the stitches being formed in the work.

FIG. 5 illustrated the position of parts of the loop taker shortly after needle loop seizure by the beak 45 and at a point in which the seized needle thread loop is first spread about the bobbin case bearing flange 76. The needle thread loop as shown in FIG. 5 will have been carried into the thread retaining notch 49 radially outward of the hook beak and that limb of the seized needle thread loop which is above the rim 44 of the loop taker body will be directed over the bobbin case bearing flange, while that limb of the seized needle thread loop which is below the hook beak and in the thread accommodating groove 47 of the loop taker body side wall will be directed beneath the bobbin case bearing flange. The constraint for the bobbin case which is provided by the abutment means 98, 99, 101, 102, 107, and 108 on the bracket 90 are preferably dimensioned so as to provide for limited clearances therebetween sufiicient to provide for the passage between the bobbin case and these abutments of the needle thread N. As illustrated in FIG. 5 the needle thread loop N caught in the notch 49 exteriorly of the beak 45 is about to be carried between the bobbin case hearing flange 76 and the abutment surfaces 98 and 101 of the bracket 90.

As illustrated in FIG. 6, rotation of the loop taker has progressed approximately 90 degrees beyond that illustrated in FIG. 5 and the needle thread loop N still caught in the notch 49 exteriorly of the loop taker beak is being carried between the bobbin case bearing flange 76 and the abutment surfaces 99 and 102 on the bracket 90. That limb of the needle thread loop which extends beneath the bobbin case will pass freely between the bobbin case and the bottom wall 41 of the loop taker body, while that limb of the needle thread loop N which extends over the bobbin case bearing flange 76 will be drawn over the central cylindrical portion 61 of the bobbin case, over the bobbin 65 and thus over the bobbin thread B. The arm 105 of the bracket 90, since it extends in chord-like fashion radially across the loop taker body will cam the seized needle thread loop radially inwardly as the needle thread loop N is carried into engagement therewith. The arm 105 will thus earn the needle thread loop from the loop seizing beak 45 and shed the loop of thread from the beak. The substantially parallel relation between the arm 105 and the slabbed surface 7% of the bobbin case bearing flange 76 provide a channel in which the shed needle thread loop will be constrained as the needle thread loop is drawn up into a stitch in the work being sewn by conventional needle thread take-up (not shown).

The loop taker of this invention as illustrated in FIGS. 5 and 6 acts simply to expand a seized needle thread loop and spread the loop about the bobbin case. The seized needle thread loop is not twisted nor folded into a tortuous path about the bobin case as it is with certain conventional rotary hooks. As a result, the action of the loop taker of this invention is remarkably gentle upon the body thread, and the stitches produced thereby are advantageously uniform in appearance.

Having thus set forth the nature of this invention, what I claim herein is:

1. A circularly moving loop taker for a sewing machine comprising a loop taker body, means journaling said loop taker body relatively to a sewing machine frame, said loop taker body including an annular rim concentric with the axis of circular movement of said loop taker body and formed with a needle loop seizing beak, said rim terminating in a flat annular bearing surface disposed substantially perpendicular to said axis, a bobbin case including a substantially cylindrical bobbin accommodating portion and a fiat bearing flange extending radially outward from said cylindrical portion and having an outer edge of which only a portion comforms to a circular are, one side of said bearing flange disposed in abutting relation against said bearing surface on said rim, and a stationary bobbin case constraining bracket, means for securing said bracket on said sewing machine frame, first means on said bracket engaging the outer edge of said bobbin case hearing flange and providing the sole constraint for said bobbin case relatively to said loop taker radially and second means on said bracket engaging the outer edge of said bobbin case bearing flange and providing the sole constraint for said bobbin case angularly, third means on said bracket engaging one side of said bobbin case hearing flange and providing the sole constraint for said bobbin case axially in a direction away from said loop taker.

2. A circularly moving loop taker as set forth in claim 1 in which said first bobbin case engaging means on said bracket includes a segment substantially equal in thickness to that of said bearing flange, said segment being positioned by said securing means adjacent to said flat annular bearing surface of said loop taker body rim, and said segment being formed with a curved surface conforming to said circular arc of said portion of the outer edge of said bearing flange.

3. A circularly moving loop taker as set forth in claim 1 in which said second bobbin case engaging means on said bracket includes an abutment positioned by said securing means for engagement with the outer edge of said bobbin case bearing flange within the axial projection of said annular bearing surface on said loop taker rim.

4. A circularly moving loop taker as set forth in claim 1 in which said third bobbin case engaging means on said bracket includes spaced abutment means positioned by said securing means overlying spaced areas of said bearing flange portion which conforms to a circular arc.

5. A circularly moving loop taker as set forth in claim 1 in which said bobbin case constraining bracket comprises one plate formed with said first bobbin case engaging means and disposed adjacent to and in a plane substantially parallel with said annular bearing surface on said loop ta ker body rim, another plate formed with both said second and third bobbin case engaging means, and in which said securing means is common to both of said plates.

6. A circularly moving loop taker as set forth in claim 1 in which said means journaling said loop taker body relatively to a sewing machine frame is adapted to provide a vertical axis for turning movement of said loop taker body.

References Cited UNITED STATES PATENTS 683,847 10/1901 Satenacci et al 112-230 1,020,041 3/1912 KieWicz l12184 1,664,032 3/1928 Hemleb l12184 1,781,427 11/1930 Barron 112-228 2,966,130 12/1960 Johnson 112-191 X HERBERT F. ROSS, Primary Examiner. 

